acids. It is adulterated with ethyl acetate, acetone, benzene and mineral
oils. Its analysis includes the following tests and determinations.1
1. Specific Gravity.This is measured by Mohr's balance or the
picnometer at 15°. The presence of amyl, ethyl, propyl alcohols, etc., acetone
or mineral oil lowers the specific gravity, whilst that of ethyl, or propyl
acetate, etc., or benzene raises it.
2. Boiling Point.100 c.c. are distilled from a flask furnished with
a thermometer, the different fractions distilling up to 100°, 100-110°, etc.,
being collected. With the exception of the mineral oils (150-170°), the
various impurities and adulterants mostly boil at lower temperatures than
pure amyl acetate (138°).
3. Non-volatile Substances.20 c.c. are evaporated slowly on a
steam-bath and any weighable residue determined. Further, a drop is
evaporated on a filter-paper and any residual oily spot observed.
4. Solubility.I c.c. is shaken with an equal volume of benzene or
carbon disulphide or with 10 c.c. of 90% alcohol and 10 c.c. of water and
note taken if a limpid solution is formed with each of these solvents.
5. Free Acids.10 c.c. are shaken with as much water and, after
standing, the aqueous liquid separated and tested with litmus paper ; or
the aqueous solution is acidified with dilute nitric acid and tested with
barium chloride (sulphuric acid] and with silver nitrate (hydrochloric acid).
6. Alcohol and Acetone.10 c.c. are shaken with an equal volume
of saturated calcium chloride and, after standing, any diminution in the
volume of the acetate observed (in a graduated cylinder any diminution
may be measured approximately). The aqueous liquid is separated and
distilled, the distillate being tested for ethyl alcohol (see Amyl Alcohol)
and acetone (see Methyl Alcohol).
If the proportion of ethyl alcohol is required, 50 c.c. of the amyl acetate
are shaken with 100 c.c. of calcium chloride solution of D = 1-25 and 30
c.c. of pure cmnene. After standing, the aqueous liquid is separated and
the supernatant amylic liquid treated with two further quantities of 50
c.c. of the calcium chloride solution. The aqueous liquids are then united
and distilled until 50 c.c. is collected, this being filtered through a dry
paper and the alcohol content determined by means of the specific gravity.
It is, of course, necessary that the product examined shall be free from
acetone and other liquids soluble in water.
7. Ethyl Acetate.10 c.c. are boiled for 30 minutes in a reflux apparatus
with 50 c.c. of a 15% solution of potassium hydroxide in amyl alcohol. The
liquid is then distilled and the first 1-2 c.c. collected shaken with water
and the aqueous liquid tested for ethyl alcohol.
For the quantitative determination, 50 c.c. of the substance and 25-30
grams of caustic potash dissolved in 50 c.c. of amyl alcohol are taken and
50 c.c. distilled over. The distillate is then treated as indicated in section
6 for the determination of the; alcohol. The alcohol by volume multiplied
by 1-508 gives the weight of ethyl acetate in 100 c.c. of the amyl acetate
1 For the analysis of amyl acetate sec also article by Chercheffski in Les matures
grasses, 1913, p. 3103.